<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>束庆乐</title>
        <style>
            p:first-child{
                color: blue;
            }
        </style>
    </head>
    <body>
        <p>This is some text</p>
        <p>This is some text</p>
        <p><b>注意: </b>对于 :first-child 工作于 IE8 以及更早版本的浏览器, ！DOCTYPE 必须已经声明</p>
    </body>
</html>